The present invention concerns a sequential control method for a display assembly including two superposed, respectively top and bottom, display devices, and more particularly a control method for a timepiece including a display assembly of the aforementioned type wherein an analogue display assembly is combined with a digital display assembly.
A so-called analogue-digital watch including a combination of analogue and digital display means is already known from European Patent No. 0 078 237 in the name of the Applicant. More precisely, this watch includes analogue time display means including an hour hand and a minute hand. These hour and minute hands are arranged above a liquid crystal display cell which forms a dial for said hands. The cell includes a hole located substantially at its centre, through which a first shaft, onto which the hour hand is fixed and a second shaft onto which the minute hand is fixed, pass. A control circuit applies a control signal across the terminals of liquid crystal display cell so that this cell displays an item of data selected from several types of data, across the terminals of the liquid crystal display cell. It may be, for example, time-related data such as the time, the minute and the second. It may also be date-related data, measured time or other data.
Other types of electronic watches including a case inside which are arranged both an analogue display device and a digital display device are also known. This is the case, for example, of a watch having a conventional analogue display device including hands moving above a dial, and a digital display device such as a liquid crystal cell arranged under the dial and visible through an aperture made in said dial.
A new type of analogue-digital watch has recently appeared. Such a watch includes a display assembly formed by an analogue display device and a digital display device. The analogue display device includes hour, minute and second hands which move above a dial, while the digital display device includes a liquid crystal display cell arranged in front of the analogue display device which it completely covers.
When the digital display device is switched into the state in which it is transparent, the data displayed by the analogue display device is perfectly visible. If, however, one chooses to use the top display device, the latter is then switched into the state in which it is opaque and reflective to totally mask the bottom display device.
Thus, when no data is displayed by the digital display device, the watch has the appearance of a conventional analogue device, i.e. the hands and the dial are completely visible through the digital display device which is transparent. Conversely, when data is displayed by the digital display device, the watch has the appearance of a purely digital watch. i.e. the hands and the dial of the analogue display device are totally masked by the digital display device and only the data displayed by the latter is visible.
It is thus possible to use either the bottom display device, or the top display device selectively, without one altering the quality and legibility of the data displayed by the other. This constitutes real progress with respect to the analogue-digital watches known to date which simultaneously display analogue data and digital data, consequently making it difficult to read such data, and this is all the more so the greater the density of data displayed.
Unfortunately, in the places where these new analogue-digital watches are exhibited in order to be marketed (for example in the window of a retail outlet), there is nothing to distinguish them from conventional analogue watches or digital watches. Indeed, either the top display cell is switched into the state in which it is transparent and in which the dial and the hands of the bottom display device are perfectly visible, and in this case the watch has the appearance of a conventional analogue watch, or the top display cell is switched into the state in which it is opaque and reflective and displays data, and in this case the bottom analogue display device is masked and the watch has a purely digital appearance. Consequently, at first sight there is nothing to enable a potential purchaser or passer-by who may pass in front of the window of the retail outlet to distinguish the analogue-digital watches of the type described above from the purely analogue or purely digital watches and fully appreciate the originality of these new products.
The object of the present invention is thus to overcome the aforementioned drawbacks, in addition to others by proposing a control method for an analogue-digital watch of the type defined above which allows a potential purchaser to distinguish such a watch from existing analogue or digital watches at a single glance.
The present invention therefore concerns a sequential control method for a display assembly including two superposed, respectively top and bottom, display devices, the top display device including at least a liquid crystal display cell and being arranged so as to be transparent in a first state to make the bottom display device visible, and so as to display a data item and to be opaque and reflective and to mask at least partially the bottom display device in a second state, control means supplying a control voltage to cause the top display device to pass from the first state to the second state and vice versa, this method being characterised in that the display assembly is made to enter an operating state wherein the top display device automatically switches in the state in which it is transparent or into the state in which it is opaque and reflective, so that the display assembly passes alternately from a mode displaying data via the top display device to a mode displaying data via the bottom display device.
As a result of these features, a potential client""s attention, stopped in front of the window of a retail outlet or in front of an exhibition stand, is drawn to the originality of the display devices including two superposed display devices by alternately switching the top display device into the state in which it is transparent or into the state in which it is opaque and reflective, so that the display assembly passes automatically from a first data display mode to a second data display mode different to the first. The passer-by""s eye will thus be drawn by this phenomenon, which should make the passer-by interested in the product in question.
According to another feature, the present invention concerns a sequential control method for a display assembly formed by an analogue data display device and a digital display device arranged in front of the analogue data display device which it covers at least partially, this method being characterised in that the display assembly is made to enter an operating mode in which the top display device automatically and alternately passes from an analogue data display mode to a digital data display mode.
Thus, when no data is displayed by the digital display device, the watch has the appearance of a conventional analogue watch. Conversely, when data is displayed by the digital display device, the watch has the appearance of a purely digital watch. Seeing the watch pass automatically from an analogue appearance to a digital appearance and vice versa, the potential purchaser immediately sees the difference which separates such a watch from conventional purely analogue or digital watches, and may fully appreciate all the advantages which this watch provides from the point of view of the originality of its design, its innovative aesthetic appearance, its ease of use and other advantages.
According to another feature of the invention, the top display device and the bottom display device are automatically and alternately activated at a frequency of the order of 0.5 Hz.
This frequency is sufficiently high for the flashing phenomenon to be immediately perceptible to the human eye, but nonetheless sufficiently slow for the human eye to be able to distinguish the details of the display in the analogue and digital modes respectively.